Ignore -N in "gzip -dN <in.gz" and "zcat -N in.gz"

Have -c override -N, like other gzip implementations. Before, our -N
(decompress to stored name) overrode -c (cat to stdout) and crashed
with a pl

Ignore -N in "gzip -dN <in.gz" and "zcat -N in.gz"

Have -c override -N, like other gzip implementations. Before, our -N
(decompress to stored name) overrode -c (cat to stdout) and crashed
with a pledge violation, because the pledge for -c excludes wpath.

Guilherme Janczak reported the pledge violation in July 2022 and
provided a diff to prevent it, along with a regress test. I rewrote
the diff and expanded the regress.

ok kn@ millert@

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Convert shell script tests to regress make rules. Having only one
tool and more verbosity allows better debugging. Additional tests
check that gzip and gunzip preserve file permissions and ownershi

Convert shell script tests to regress make rules. Having only one
tool and more verbosity allows better debugging. Additional tests
check that gzip and gunzip preserve file permissions and ownership.

show more ...

Regression tests for gzip(1):
- Test if we detect truncated or corrupted files.
- Test basic functionality
OK millert@, markus@